Aircraft heater with air-driven fuel pump



April 1947- H. J. DE N. M coLLuM 2 AIRCRAFT HEATER WITH AIR-DRIVEN FUEL PUMP Filed May 10, 1943 5 Sheets-Sheet l April .1947- H, .1. DE N. M COLLUM' 18,720

AIRCRAFT HEATER WITH AIR-DRIVEN FUEL PUMP Filed May 10, 1943 3 Sheets-Sheet 2 Milli/ 551 April 1947- H. DE N. M COLLUM 2,413,720

AIRCRAFT HEATER WITH AIR-DRIVEN FUEL PUMP Filed llay 10, 1943 3 Sheets-Sheet 3 pumping mecha Fig. 3;

Fig. 6 is a transverse, sectional view through Fatented Apr. 8,1947

' UNITED STATES Hiram" AIRCRAFT HEATER wrrn AIR-D FUEL PUMP Henry J. De'N. McCollum, Chicago, Ill.; Thelma McColium, executrix of'said Henry J. De N- McCollum,

deceased, assignor to Stewart- Warner Corporation, Chicago, 111., a corporation of Virginia Claims.

My invention relates to aircraft heaters and more particularly to aircraft heaters of the internal combustion type.

An object of my invention is to provide a new and improved aircraft heater wherein the fuel delivered to the combustion chamber of. the heater bears the proper relation to the rate of flow of ventilating air through the heater.

Another object of my invention is to provide a new and improved heater which is adapted to be supplied with'fuel from the boosterpump 7 which supplies fuel to an engine of the aircraft Fig. '7 is a sectional vie through a loaded check valve taken on line 1-1 of Fig. 1; v

Fig. 8 is a longitudinal, sectional view throng a modified form of fuel pump; I Fig. 9 is a transverse, sectional view of the fuel pump of Fig. 8 and is taken on the line 8-9 of this figure;

Fig. 10 is a view similar to Fig. 1 but showing the heater in side elevation and indicating more clearly the manner in which this heater supplies heated air to the duct leading to thecabin of the aircraft; and

Fig. 11 is a fragmentary view similar to Fig. 10, but showing a modified form of my invention in which a solenoid fuel control valve is substituted .for the check valve of the form shown in Fig. 10.

cated generally by reference numeral having heaterv needs and is automatically turned on and ofi by merely turning on or shutting oil the sup ply of ventilating air to the heater.

Another object of my invention is to provide a ram operated heater wherein the fuel supply a combustion chamber 22 which supplies hot products of combustion to the gas passages 2% in a heat exchanger indicated generally by ref- 1 erence numeral 28. The heat exchanger 26 comto the heater is automatically controlled by controlling the air delivery from the ram to th heater having new and improved fuel supply means.

Other objects and advantages will become apparent as the description proceeds.

In the drawings:

Fig. 1 is a diagrammatic representation of a heater installation embodying my invention and shows the heater in longitudinal section;

Fig. 2 is a transverse, sectional view of the heater taken on the line 2-2 oi Fig. 1;

Fig. 3 is a longitudinal. sectional view through the fuel pumping means and is taken on the line M of Fig. 1;

Fig. 4 is a transverse, sectional view of the driving magnetic assembly and is taken on the line M of Fig. 3;

Fig. 5 is a transverse, sectional view of the taken on the line 8-45 of owls-3;

prises a corrugated cylindrical shell 28 having fins 80 clamped between the corrugations thereof. These fins project into a ventilating air passage 82 formed between the shell 28 and a cylindrical casing at which encloses thecombustion chamber 22 and heat exchanger 28.

The gas passages 24 are formed between the outermost portions of the shell 28 and a mufiier 36 formed of sheet metal construction and divided into compartments 38 containing glass wool or stainless steel wool or similar sound absorbing material. An annular row of small openings to forms acoustic couplings between each compartment and the gas passages it. As the hot gases enter an exhaust pipe it through which they are discharged to atmosphere.

The lefthand end of the heater casing 36 is tapered, as indicated at dd, and connects with a pipe 86 leading from a ram, blower, or other suit able source of supply. In Fig. 10 I have shown a typical installation in which the ram d7 supplies ventilating air to the heater and wherein a shut or vary in any suitable manner the flow of venti lating air to the heater. A heater installation having such a ram and variable shutter is shown in my co-pending application Serial No. 413,463, filed October 3, 1941, now Patent No. 2,364,458

issued December 5, was. This ventilating air passes over the combustion chamber 22 and fins 20 and absorbs heat therefrom. The heated ventilating air passes from the righthand end of the casing 34 into a tapered outlet 48 communicating with a pip 50 leading to the-aircraft cabin or other space or spaces .to be heated.

. Partof the heated air is diverted into a pipe 52 connected to an induction tube 54 having a discharge end 56 located in the lefthand end of the combustion chamber and so positioned as to deliver a mixture of fuel and air to this chamber in a direction tangential to the circular wall thereof. A jet 58 supplies fuel to the inlet end of the induction pipe 54 and the fuel and air mixture delivered to the combustion chamber is ignited by,a coil 60 forming part of an igniter plug 62 threaded into a housing 64 attached to the wall of the combustion chamber. This housing provides a pocket 66 which. communicates with the interior of the combustion chamber by way of inlet 68 and outlet 10. This igniter is ordinarily disconnected from its source of current after the heater attains normal operating temperature and a re-igniter 12 is provided to maintain combustion thereafter.

Fuel is supplied to the jet 58 from the main fuel tanks of the aircraft by means of the booster located in the tapered inlet 44 of the heater casf, Ing and functions to supply fuel to the jet 68 by way of pipes 92 and 94 and past check valve 96.

The valve 96 is best shown in Fig. 7 and com- I prises a body 88 having an inlet port I00 and an outlet I02. The inlet port I00 is in communication with pipe 92 leading from pump 88 and is normally closed by a ball check I06 urged lator 84 is necessary to open the valve. Pump 88 provides the necessary additional pressure to open this valve and force fuel to th heater jet 66, but no fuel is supplied to this Jet except when the pump 68 is being driven by its impeller 90.

4 cular recess I30 in the housing H6 and the circular configuration of the assembly II8 prevents such rotation fromereating unnecessary air currents in the recess.

The housing I I6 is secured to a second housing I 32 by bolts I34 and a non-magnetic diaphragm I 36 is clamped between the housings and serves to seal the otherwise open end of a pumping chamber I38 formed in the housing I32. The pump rotor is mounted in this pumping chamber I38 and comprises a permanent magnet I40 mounted on a shaft I42 having one end supported in a bearing I44 carried by the diaphragm I36 and a second end supported in a. bearin I46 mounted in the housing I32. The bearing I46 is provided with a screw adjustment I48, which is accessible through the inlet opening to which the pipe 86 is attached.

A non-magnetic plate .I50 is secured to the magnet I40 by rivets I52 and non-magnetic members I54 and I56 are secured to the plate I50 by rivets I58 and I60. Vanes or blades I62 are welded to the plate I50. The pumping chamber I38 is provided witha tangentially arranged outlet I64 in communication with the pipe 92 leading to the valve 96'. The housings H6 and I32 are preferably die' cast of non-magnetic material.

When the impeller is driven by air entering the inlet end of the heater casing, this impeller rotates shaft H0 and magnetic assembly II8. Magnet I 40 rotates with magnet I22 of assembly H8,

thereby causing a rotation of the blades or vanes projecting into the pump chamber.

In Figs. 8 and 9, I have shown a modified form of pump and driving means therefor; comprising a shaft I10 which is adapted to have th fan 90 attached to one end thereof. This shaft is sup ported in roller bearings carried by a housing I12 i to which a second housing I14 is secured'by bolts,

When heat is desired and the ram is permitted to supply air to the inlet end of the heater casing, the inflow of air rotates impeller 90, which In turn drives pump 88 to force fuel past valve 96 and thence to jet 68. The pump 88 may be of any suitable type, but a pump and driving means therefor which are particularly advantageous for this use are shown in detail in Figs. 3, 4, 5 and 6. Referring to these latter figures, it will be seen that the impeller 90 is mounted on one end of a driving shaft I I0 by a set screw I I l and this shaft or in any other suitable manner. ---A diaphragm I16is clamped between the housings I12 and I14 sealed against escape of fuel by a rotating ring.

I82 having a. narrow annular edge engaging the plate I16. This ring is carried in one end of a resilient Sylphon I84 and the other end of this 'Sylphon is attached to a flange I86 which may form an integral part of the shaft I10.

A pump rotor I88 is located in the chamber I18 and rotates with the shaft, I10. This rotor I88 has slots I90 for vanes I92 which slide in these slots as the rotor turns in the eccentric pumping chamber I18. This chamber has a fuel inlet I94 to which the pipe 86 is attached and an outlet I96 to which the pipe 92 is attached. 4

As the airplane increases its altitude, the air becomes thinner and unless altitude compensating means is provided, the mixture of fuel and air-delivered to the combustion chamber of the.

heater will become richer. The pump of Figs. 8 and 9 is provided with an altitude compensating bypass I98 to maintain a uniform richness of mixture for all altitudes. This bypass includes a re aciavao strictlon 200 and a needle valve 202 which is moved in and out of this restriction to variably the needle valve 202 with the righthand or movable end of the bellows .208. As atmospheric pressure decreases with increase in altitude, spring 208 expands bellows 204 and moves needle valve 202 to the right, thereby permitting increasing flow through the bypass-and thus reducing the quantity of fuel supplied to the'heater Jet 58. A resilient Sylphon 209 forms a seal between the needle valve 202 and the bypass wall.

The pump housing H6 is supported in a sheet metal frame 2l2 attached to the heater casing 34 by screws 2M. This frame provides a, convenient means of mounting the pump and impeller in the inlet end of the heater casing, although any other suitable mounting means may be provided, The particular combustion chamber, heat exchanger and muiiier disclosed herein are claimed in my copending applications, Serial Nos. 477,080, filed February 25, 1943; 476,266, filed February 18, 1943 and now Patent No. 2,404,646; and 478,259, filed March 6, 1943, and other types of combustion chambers, heat exchangers and muiliers may be used in lieu of the particular ones shown herein.

While the loaded check valve 86 constitutes a convenient and effective means for preventing flow of fuel to the jet 58 when no ventilating air heater. If this air flow is decreased by partly or completely closing or cutting oi? the rain which supplies air to the heater, or by partly or completely closing any or all shutter mechanism interposed between the outlet end ofv the heater and the space or spaces into which the heated air is discharged, the fuel supply for the heater will be correspondingly reduced so that the quantity i of fuel consumed by the heater is never more than that necessary properly to heat the quantity of ventilating air which is flowing through the heater at any given time. This regulation'ofthe fuel supply is entirely automatic and requires no effort or attention on the part of. the pilot or crew of the airplane. I

It is to be understood that my invention is not limited to the particular details shown and described, but may assume numerou 'other forms and that the scope of my invention includes all modifications and variations coming within the V scope of the appended claims.

is flowing through the heater, this check valve may be replaced by a solenoid'valve which is en-' ere'izfid whenever the heater is operated. Such a solenoid valveis indicated by reference character 98' in Fig. 11. The jet-50, to which the fuel is supplied, discharges this fuel into the air flowing through the induction tube 54 under pump pressure and requires no restriction in this tubeto create a suction at the let outlet.

. said Jet with a booster pump for supplying fuel to an airplane engine, a pressure regulator in Such a jet arrangement is especially desirable,.

since it permits freer flow to the combustion chamber, whereas the usual carburetor, with its restrictive Venturi tube, would increase the pressure drop between the combustion chamber and. the outlet end of the heat exchanger. While any increase in. pressure drop is undesirable, a carburetor could be substituted for the jet arrange-' ment shown in the drawings and my invention is to be considered as contemplating the substitution of a carburetor for the jet 58 whenever the use of a carburetor is desired. In the drawings, I have shown all fuel as being supplied to a single jet. but it is to be understood that two or more 7 Jets may be utilized in lieu of the single jet shown in the-drawing for illustrative purposes.

In the drawings, I have shown the heater as being supplied with fuel from the booster pump which is primarily provided for .the purpose of furnishing fuel to the airplane engine or engines.

' This booster-pump provides a convenient source of fuel for the heater, but whenever it is more desirable to do so, a separate source'of fuel may be provided for the heater and such separate source of fuel may take any desired form, such for example, as. a fuel tank from which the fuel flows by gravity to the impeller driven pump I32.

Where such a fuel supply is provided. it will usuvalve 95 shown in' Iclaim: 1. An aircraft heater of the class described,

4 comprising means forming a combustion-chamber, an induction tube for supplying combustible mixture to said chamber, a let for supplying fuel to said combustion chamber, a heat exchanger receiving hot products of combustion from said combustion chamber, a casing enclosing said combustion chamber and heat exchanger, said casing having a tapered end adapted tobe connected with a ram, said casing also having an outlet through which at least most of the air supplied by said ram is discharged as heated air for ventilating purposes, piping means for connecting said piping means for limiting the pressure created by said booster pump to an absolute maximum, a check valve interposed between said pressure regulator and said jet and openable only under a pressure greater than said absolute maximum pressure, a pumpinsaid casing interposed between said pressure regulator and said valve and operable to force fuel past-said valve to said Jet, and an impeller responsive to air flowing through said casing for driving said pump at ditferent speeds varying with the rate of air flow.

2. An aircraft heater of the class described, comprising a cylindrical casing connected to a source of air for ventilating purposes, said casing having an outlet through which at least most of the air entering said casing is discharged as heated air for ventilating purposes, means forming a combustion chamber located in said casing, a heat exchanger located in said casing and receiving hot gases from said combustion chamber,

. a pump for supplying fuel to said combustion titude controlled. bypass for said pump for reduca .ing the quantity of fuel supplied to said combuschamber, an impeller in said casing for driving said pump, said impeller being rotatedby ventilating air flowing through said casing, and an altion chamber at higher altitudes.

3. An aircraft heater of the class described, comprising means forming a combustion chain her, an induction tube for supplying combustible mixture to said chamber, means for supplying fuel to said combustion chamber, a heat as changer receiving hot products of combustion from said combustion chamber, a casing enclosing said-combustion chamberand heat exchanger, piping means for connecting said means with a booster pump for supplying fuel "to an airplane engine, a pressure regulator in said piping means I 7 for limiting the pressure created by said booster pump to an absolute maximum, a check valve interposed between said pressure regulator and said means and opcnable only under a pressure greater than said absolute maximum pressure, a pumpin said casing interposed between said pressure regulator and said valve and operable to force fuel past said valve to said means, means for causing air to flow through said casing and over said heat exchanger, and an impeller operated by said flowing air to drive said pump at diflerent speeds.

'4. An aircraft heater or the class described, comprising a cylindrical casing connected toa source of ventilating air, said casing having an outlet through which at least most of the air entering said casing is discharged as ventilatins air, means forming a combustion chamber located in said casing, a heat exchanger located in said casing and receiving hot gases from said combustion chamber, a pump in said casing for supplying fuel to said combustion chamber, an impeller in said casing and variably driven by said ventilating air for driving said pump, a bypass for said pump for reducing the quantity of fuel supplied to said combustion chamber at higher altitudes,.and pressure-respsnsive means pressure. a

5. A heater 'oLthe class described, comprising a tubular casing connected to a source of venti.

lating air, said casing having an outlet through which at least most of the air entering said casing is discharged as ventilating air, means forming' a combustion chamber located therein, a heat exchanger connected to said combustion chamber and receiving hot gases therefrom, a centrifugal pump for supplying fuel to said combustion chamber, means variably operated by said ventilating air for driving said pump, a loaded check valve interposed between saidpump and combustion chamber, and means for supplying fuel to said pump at a pressure less than that required to open said check valve, and an altitude HENRY J. Dr: N. McCOI-LUM.

REFERENCES CITED The following references are of record in the file of 'this patent:

Hunter M81310, 1936 Certificate of Correction Patent No. 2,418,720. April 8, 1947'.

HENRY J. DEN. MoCOLLUM 7 It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Column 8, line 14, claim 5, after altitude insert the words and period controlled bypass for said said Letters Patent should be read with this correction therein conform to the record of the case in the Patent Ofiice.

Signed and sealed this 3rd day of June, A. D. 1947.

LESLIE FRAZER,

First Assistant Commissioner of Patents. 

